GRPCK(8)                                                              GRPCK(8)


       grpck - verify integrity of group files


       grpck [-r] [group shadow]


        grpck verifies the integrity of the system authentication information.
       All entries in the /etc/group and /etc/gshadow are checked to see that
       the entry has the proper format and valid data in each field. The user
       is prompted to delete entries that are improperly formatted or which
       have other uncorrectable errors.

       Checks are made to verify that each entry has:

       ·  the correct number of fields

       ·  a unique group name

       ·  a valid list of members and administrators

       The checks for correct number of fields and unique group name are
       fatal. If the entry has the wrong number of fields, the user will be
       prompted to delete the entire line. If the user does not answer
       affirmatively, all further checks are bypassed. An entry with a
       duplicated group name is prompted for deletion, but the remaining
       checks will still be made. All other errors are warnings and the user
       is encouraged to run the groupmod command to correct the error.

       The commands which operate on the /etc/group file are not able to alter
       corrupted or duplicated entries.  grpck should be used in those
       circumstances to remove the offending entry.


       By default, grpck operates on the files /etc/group and /etc/gshadow.
       The user may select alternate files with the group and shadow
       parameters. Additionally, the user may execute the command in read-only
       mode by specifying the -r flag. This causes all questions regarding
       changes to be answered no without user intervention.  grpck can also
       sort entries in /etc/group and /etc/gshadow by GID. To run it in sort
       mode pass it -s flag. No checks are performed then, it just sorts.


              group account information

              secure group account information

              user account information


       group(5), passwd(5), shadow(5), groupmod(8)


       The grpck command exits with the following values:

       0      success

       1      invalid command syntax

       2      one or more bad group entries

       3      can’t open group files

       4      can’t lock group files

       5      can’t update group files


       Julianne Frances Haugh (

                                  08/03/2005                          GRPCK(8)

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